1. Field of the Invention
The present invention relates to a video processing apparatus that displays, on a display unit, video data including frame-image data for left-eye and frame-image data for right-eye such that a user can stereoscopically view an image represented by the video data, and to a control method therefor.
2. Description of the Related Art
Hitherto, a stereoscopic system has been known, which implements stereovision by displaying a three-dimensional (3D) image that utilizes a binocular parallax and that includes a image for left-eye and a image for right-eye. Such a stereoscopic system employs the following method. The method generates a parallax by shifting, in a direction of an interpupillary distance, the display positions of a frame-image for left-eye and a frame-image for right-eye represented by image data Consequently, the method implements stereoscopic effects of various objects included in an image represented by the video data. To prevent a user from having a discomfort feeling due to a large amount of projection of an object, it has been proposed to control the stereoscopic appearances of the object by adjusting a parallax amount that is a shift amount in the direction of the interpupillary distance between the images of the object within a set of a frame-image for left-eye and a frame-image for right-eye.
Japanese patent Application Publication No. 11-164328 discusses techniques in which when switching between 3D-images different in parallax amount or switching from a two-dimensional (2D) image to a 3D-image, an original 3D-image is displayed as a 2D-image and then returned to the original 3D-image so as to reduce a burden to eyes. When the parallax amount is put back to the original 3D-image, an acceptable threshold for the parallax amount is gradually increased with time.
The above techniques can suppress the stereoscopic effects of an object to be displayed when switching to a 3D-image. However, when returning to an original 3D-image after that, a moving speed in an anteroposterior direction (depth direction) of an object to be perceived is not considered. Depending on relationship between the moving speed of the object and the acceptable threshold, a user may perceive that the object is accelerated at a speed higher than an original moving speed and approaches him, and may be surprised.